Electric relay



Feb. 10. 1925.

1,526,099 0. s. SNAVEL ELECTRIC RELAY med oct. 2 1923 r1: "L i l m INVENTORf F g/u amw Patented Feb. 10, 1925.

UNITED STATES PATENT OFFICE.

CLARENCE S. SNAVELY, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

ELECTRIC RELAY.

Application filed. October 24, 1923.

To all whom it may concern:

Be it known that I, CLARENCE S. SNAX LY, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Electric Relays, of which the following is a specification.

My invention relates to electric relays, and particularly to contact mechanism for relays.

I will describe two forms of relay contact mechanism embodying my invention, and will then point outthe novel features thereof in claims.

In the accompanying drawings, 1 is a view showing, in front elevation, a relay having one form of contact mechanism embodying my invention. Fig. 2 is a view showing a modification of the contact mechanism of Fig. 1 and also embodying my invention. Fig. 3 is a view showing the contact mechanism of Fig. 2 as viewed from the left.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference character A designates the base plate of a relay. This plate A is of some suit-able insulating material such as porcelain and carries an electromagnet B. The core 1 of this magnet passes through the plate A and terminates, on the under side of the plate, in a pole face 2. Secured to the side of pole face 2 by means of a screw 4 is a bracket 3. An armature 6 of suitable magnetizable material such as soft iron is pivotally supported at point 5 by bracket 3 and is arranged to be drawn upward toward pole face 2 when magnet B is energized. Attached to this armature 6 by means of insulating studs 7 is a contact arm C secured to the studs by means of nuts 7*. The left hand end of this arm is bent upward at an angle with the body of the arm and the tip of this bent portion is offset to form the lower leg 12 of a yoke. The other leg 13 of this yoke is fastened to leg 12 by means of rivets 17 Interposed between these two le s 12 and 13 and extending outwardly therebetween is a flexible conducting spring contact finger 14 provided at its upper ex- Serial No. 670,447.

tremity with a low resistance contact tip 16 of some suitable material such as silver, which tip co-acts with a fixed contact member 11.

hen magnet B is tie-energized, contact arm C drops down against stop 23 under the influence of gravity, but when this magnet is energized the arm C swings up ward till armature 6 strikes pin 21 in pole face 2. During this motion contact finger 14; engages the fixed contact member 11.

If arm C is in its lower position and magnet B becomes energized, armature 6 is moved upward but the force exerted by the magnet increases as the armature approaches the pole face. Soon after this motion commences, finger 14 engages contact 11 and thereafter arm 14- is flexed or bent, thus increasing the pressure of contact and decreasing, therefore, the electrical resistance of the contact. It is desirable to make this pressure as heavy as possible for a given energization of magnet B. If spring finger 1 1 is too stiff, the force exerted by magnet B will not be suflicient to complete the stroke of armature 6. If, on the other hand, the spring finger 14 is sufliciently weak to permit the armature 6 to complete its stroke, the pressure exerted by the spring at full stroke is much less than the force exerted by the magnet since the pressure exerted by finger 14 is directly proportional to the deformation in this member and hence to the motion of armature 6, whereas the force exerted by magnet B increases inversely as the distance between the pole face and the armature according to some function of this distance greater than unity. It is therefore plain that to gain the maximum of advantage from the pull exerted by the actuating magnet, the stiffness of spring finger 14 should be progressively increased asthe armature moves through its stroke. One method of accomplishing this resultis shown in the drawing in which a plurality of screws 18, 19 and 20 are adjustably inserted in leg 12 to engage the back of finger 1aduring the operation of the contact. As the armature moves upward, finger 14 engages first screw 20, then screw 19, and finally, just before the end of the stroke, screw 18. t will be plain that 11, magnet B is exerting a certain force upon "the armature. The bending stress of finger M when the contact 15 open 15 ad- ]usted,.by means of screw 15, threaded in top leg 13, so that the force required to bend the finger away from the screw will be slightly less than that exerted; by magnet B at the instant of contact.

Referringnow to Figs. 2 and 3, in the mechanism here shown, the screw 15 of F ig, 1 is replaced by a downwardly projecting end 13? of top leg 13 which engages the upper surface offfinger 14 'for the" purpose explained hereinbefore. In place ofyscrews 18 19, and 20, the lower leg 12 ofarm C is of accurate form alndhas its right hand end in contact with the lower side of spring finger 1%, As the finger 1a is flexed downward itrolls along the shank ofleg 12, and thereby constantly changes the resistance offered by finger 14 to fiexure of; the finger.

Although I have herein shown and de-, scribed only two forms of apparatus em bodying my invention, it is understOQdl that various changes and: modifications may made therein within the, scope o f-the appended claims without departing from the spirit andscope of myinvention.

Having thus described my invention, what I claim is:

1. In combination, anelectromagnet, an armature controlled thereby, a fixed con tact member, a spring contact finger moved into engagement with said member by said armature when the magnet becomes energized, whereby the force exerted on said finger increases as the armatureapproaches the magnet, the parts being so arranged that the the finger engages the member be fore. the motion of the armature is completed, and means for progressively increas ing the stiffness, of said finger from the time the finger engages the fixed member to the time, the motion of the armature is completed. i

2. 'InYcombination, an. electromagnet, an

armature controlled thereby, a fixed contact member, a spring contact finger moved into engagement with said member by said armature when the magnetpbecomes 'energized, whereby the, force exerted on said finger increases as the armature approaches the; magnet, the parts being so arranged that the finger engages the 'member before the motion of the armature is completed, and means for progressively decreasing. the effective length of said finger from the time the V fingerl engages the fixed member to the time the motion plejted;

In testimony whereof I aflix my signature.

CLA'RENCE S. SN'AVELY.

ofthe. armature is com 

